Systems for the recognition of road signs can be used to inform the driver of a motor vehicle of the road signs at the road, for example by projection onto the windshield of the motor vehicle via a head-up display of a graphic representation of a road sign detected at the road. Systems for the recognition of road signs can, however, also be used as driver assistance systems, for example to automatically reduce the driving speed to the permitted maximum speed when speeding.
Cameras are used for road sign recognition which take the environment in front of the motor vehicle and examine it for the presence of road signs. A road sign recognition can, for example, be carried out in two stages. In a first stage (detection), it is then a question of locating potential candidates for images of road signs in a taken picture via a feature extraction. This can take place, for example, by means of a Hough transformation which serves for the recognition of geometrical shapes or by means of a color segmentation in which contiguous areas of the same color are recognized. The second stage (classification) has the object of first determining whether the respective candidate is actually an image of a road sign and, in the affirmative case, of then determining the type of the imaged road sign. This can be done, for example by means of template matching.
Such a road sign recognition, which is carried out by a data processing device, however, requires a high computing effort which results in a high computing time. The robustness of such a road sign recognition is furthermore insufficient.